Intravascular catheter with composite reinforcement

ABSTRACT

An intravascular catheter that exhibits the combined features of superior flexibility, softness, radiopacity and oval/kink resistance. The catheter includes an elongate shaft having a proximal region, a distal region and a lumen extending therethrough. The proximal region of the shaft includes an inner lubricious polymer layer, a reinforcement layer and an outer layer. The reinforcement layer comprises a braid having one or more metallic members and a plurality of polymer members wherein each polymer member comprises a plurality of monofilaments, preferably formed of LCP. The polymer members of the braid provide improved flexibility and softness in addition to high burst pressure. The metallic member(s) of the braid provide improved radiopacity and oval/kink resistance. The catheter may also include a longitudinal member extending along the reinforcement layer.

This application is a continuation of U.S. patent application Ser. No.09/234,203, filed on Jan. 20, 1999, now U.S. Pat. No. 6,171,295.

BACKGROUND OF THE INVENTION

The present invention generally relates to intravascular devices. Morespecifically, the present invention relates to reinforced intravascularcatheters.

Intravascular catheters are used in a wide variety of relativelynon-invasive medical procedures. Such intravascular catheters may beused for diagnostic or therapeutic purposes. Generally, an intravascularcatheter allows a physician to remotely perform a medical procedure byinserting the catheter into the vascular system of the patient at alocation that is easily accessible and thereafter navigating thecatheter to the desired target site. By this method, virtually anytarget site in the patient's vascular system may be remotely accessed,including the coronary, cerebral, and peripheral vasculature.

The distance between the access site and the target site is often inexcess of 100 cm. The inside diameter of the vasculature at the accesssite is often less than 2 cm, and the inside diameter of the vasculatureat the target site is often less than 0.5 cm. Accordingly, intravascularcatheters must be relatively long and thin. Furthermore, in order tonavigate through the patient's tortuous vascular system, intravascularcatheters must be very flexible. It is also desirable that intravascularcatheters be relatively soft in order to minimize the probability ofdamaging vascular tissue.

Intravascular catheters typically have a radiopaque portion and areguided through the patient's vascular system with the assistance ofx-ray fluoroscopy. In this manner, a physician may manipulate theproximal end of the catheter and fluoroscopically monitor thecorresponding movement of the distal end of the catheter. As such, it isdesirable that intravascular catheters be sufficiently radiopaque alongtheir length and particularly at their distal end such that thephysician is able to clearly monitor the progress of the catheter as itis being advanced from the vascular access site to the vascular targetsite.

After the intravascular catheter has been navigated through thepatient's vascular system with the distal end thereof adjacent thetarget site, the catheter may be used for various diagnostic and/ortherapeutic purposes. Frequently, diagnostic and therapeutic techniquesrequire the infusion of fluids through the catheter. For example, it maybe desirable to inject radiopaque contrast media through the catheter toprovide enhanced fluoroscopic visualization for diagnostic purposes, orto inject pharmaceutical solutions (i.e., drugs) to the target site fortherapeutic purposes. In order to maintain a fluid path, it is desirablethat intravascular catheters be sufficiently resistant to kinking. Inaddition, because such fluids are delivered under pressure, it is alsodesirable that intravascular catheters be sufficiently resistant tobursting.

To satisfy some of these desirable features, prior art intravascularcatheters have utilized a reinforcement structure such as a braid orcoil disposed between an inner lubricious tubular layer and an outerflexible tubular layer. A braid reinforcement structure offers highresistance to bursting and improves the connection integrity betweenindividual shaft segments. However, braid reinforcement offers limitedresistance to ovaling, which is a precursor to kinking. A coilreinforcement structure, by contrast, provides adequate resistance toovaling and kinking, but does not sufficiently enhance the connectionintegrity between individual shaft segments.

SUMMARY OF THE INVENTION

The present invention overcomes these disadvantages by providing anintravascular catheter that exhibits the combined features of superiorflexibility, softness, radiopacity, durability, high burst strength, andoval/kink resistance.

An intravascular catheter in accordance with one embodiment of thepresent invention includes an elongate shaft having a proximal region, adistal region and a lumen extending therethrough. The proximal region ofthe shaft includes an inner lubricious polymer layer, a reinforcementlayer and an outer layer. The reinforcement layer comprises a braidhaving at least one metallic member and a plurality of polymer memberswherein each polymer member comprises a plurality of monofilaments. Themonofilaments may be made of LCP having a substantially circularcross-section and may be unfused or fused together. The monofilamentsmay be arranged side-by-side to collectively define a flat cable thatmay be twisted along the length of the shaft. The metallic member(s) maybe made of a highly radiopaque material. The catheter may furtherinclude a longitudinal member extending along the reinforcement layer.The longitudinal member may also comprise a plurality of longitudinalmonofilaments made of a polymer, such as LCP. The distal region of theshaft may include a radiopaque marker band surrounding the reinforcementlayer and an atraumatic tip layer surrounding a portion of theradiopaque marker band and a portion of the reinforcement layer. The tiplayer may extend distally beyond the distal ends of the inner layer andthe reinforcement layer to form an atraumatic soft distal tip.

The brand reinforcement provides high burst strength and durability. Thepolymer members of the braid provide enhanced flexibility and softness,and the metallic members(s) of the braid provide enhanced radiopacityand resistance to ovaling and kinking. These combined features are notfound in the prior art.

An intravascular catheter in accordance with another embodiment of thepresent invention includes an elongate shaft having a proximal region, adistal region and a lumen extending therethrough. The proximal region ofthe shaft includes an inner lubricious polymer layer, a reinforcementlayer and an outer layer. The outer layer includes a proximal portionmade of a first material having a first durometer, and a distal portionmade of a second material having a second durometer less than the firstdurometer. The reinforcement layer comprises a braid having one or moremetallic members and a plurality of polymer members wherein each polymermember comprises a plurality of monofilaments. The distal region of theshaft includes a radiopaque marker band surrounding the reinforcementlayer and an atraumatic tip layer surrounding the radiopaque marker bandand the reinforcement layer. The tip layer is made of a third materialhaving a third durometer less than the second durometer. The tip layerincludes a distal portion that extends beyond the distal ends of theinner layer and the reinforcement layer to form an atraumatic softdistal tip.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view of an intravascular catheter in accordance withthe present invention;

FIG. 2 is a partially sectioned detailed view of the elongate shaft ofthe intravascular catheter illustrated in FIG. 1. Specifically, theouter layer has been removed on the top portion of the shaft to exposethe reinforcement layer and the radiopaque marker band. In addition, thebottom portion has been sectioned to expose the various layers of theshaft;

FIG. 3 is a cross-sectional view taken along line 3—3 in FIG. 1;

FIG. 4 is an alternative embodiment of the shaft illustrated in FIG. 2;and

FIGS. 5A and 5B are cross-sectional views of the polymer member of thereinforcement layer illustrated in FIGS. 2-4.

DETAILED DESCRIPTION OF THE INVENTION

The following detailed description should be read with reference to thedrawings in which similar elements in different drawings are numberedthe same. The drawings, which are not necessarily to scale, depictillustrative embodiments and are not intended to limit the scope of theinvention.

FIG. 1 illustrates intravascular catheter 10 in accordance with thepresent invention. Catheter 10 includes an elongate shaft 12 having aproximal region 14 and a distal region 16. The catheter 10 includes alumen 18 (as best seen in FIG. 3) extending through the entire length ofthe elongate shaft 12 to an opening at the distal end 20 of the shaft12. Catheter 10 may have a length of 80 to 150 cm and an outsidediameter of approximately 3F.

A manifold 24 is connected to the proximal end 22 of the shaft 12 whichincludes an interior (not visible) in fluid communication with the lumen18 of the elongate shaft 12. Manifold 24 includes a standard fitting 26for connection to a fluid source such as a syringe. A strain relief 28is disposed between the manifold 24 and the proximal end 22 of the shaft12 in order to reduce the tendency of the shaft to kink therebetween.The proximal end 22 of the elongate shaft 12 may extend through thestrain relief 28 for connection to the manifold 24. Alternatively, thedistal end of the strain relief 28 may be connected to the proximal end22 of the elongate shaft 12 with the proximal end of the strain relief12 connected to the manifold 24.

With either arrangement, the intravascular catheter 10 provides a fluidpath from the fitting 26 of the manifold 24 to the distal end 20 of theelongate shaft 12 by way of the interior (not visible) of the manifold24 and the lumen 18 of the elongate shaft 12. This intravascularcatheter 10 may be advanced over a guide wire and used to deliverdiagnostic and/or therapeutic fluids to a desired vascular target siteusing conventional techniques.

FIG. 2 is a partially sectioned detailed view of the elongate shaft 12of the intravascular catheter 10 illustrated in FIG. 1. On the topportion of the shaft 12, the outer layer 30 has been removed to exposethe reinforcement layer 32 and the longitudinal member 34. On the bottomportion, the shaft 12 has been sectioned to illustrate the variouslayers 30, 32, 36, and 38 of the shaft 12.

Elongate shaft 12 includes a proximal region 14 and a distal region 16.Both the proximal region 14 and a portion of the distal region 16include an inner lubricious polymer layer 36 surrounded by areinforcement layer 32 which, in turn, is surrounded by an outer layer30. The outer layer 30 may be loaded with a radiopaque contrast materialsuch as barium sulfate, preferably loaded at 30% by weight. A tie layer38 may be provided between the reinforcement layer 32 and the innerlubricious layer 36. Each of these layers are most clearly illustratedon the bottom portion of the shaft 12 shown in FIG. 2 and thecross-sectional view taken along line 3—3 as shown in FIG. 3.

Inner layer 36 is formed of a lubricious polymer such as PTFE or HDPEand preferably has a relatively thin wall to minimize profile. Innerlayer 26 has an inside diameter sufficiently large to accommodate aconventional guidewire and to accommodate the delivery of fluidstherethrough at a sufficient flow rate. For example, the inside diameterof the inner layer 36 may be approximately 0.027 inches and the wallthickness of the inner layer 36 may be approximately 0.0005 inches. Theinner layer 36 may be formed, for example, by coating or extruding alubricious polymer such as PTFE over a removable mandrel, or by usingother known manufacturing techniques.

As mentioned previously, a tie layer 38 may be utilized to secure thereinforcement layer 32 to the inner lubricious layer 36. Tie layer 38enhances the bond between the inner lubricious layer 36, thereinforcement layer 32, and the outer layer 30. Tie layer 38 also fillsany micro-pores that may form in the inner layer 36 to thereby increaseburst strength. Further, tie layer 38 maintains the position of thereinforcement layer 32 on the inner layer 36 during the manufacturingprocess. The thickness of the tie layer 38 may be approximately 0.0003inches to reduce the corresponding increase in profile. An example of asuitable material for tie layer 38 is polyurethane, which may be coatedonto the inner lubricious layer 36.

Reinforcement layer 32 comprises a plurality of braided polymer members40 and one or more metallic members 42. For example, the reinforcementlayer 32 in the form of a braid having a total of eight members maycomprise six polymer members 40 and two metallic members 42. Thoseskilled in the art will recognize that the braid reinforcement layer 32may vary in pattern, strand quantity, pick-count, etc., withoutdeparting from the scope of the present invention.

Each polymer member 40 comprises a plurality of monofilaments 41 tocollectively define a cable 40A or 40B, illustrated in FIGS. 5A and 5B,respectively. FIGS. 5A and 5B show cross-sectional views of the polymercables 40A and 40B of the reinforcement layer. FIG. 5A illustrates around cable 40A, and FIG. 5B illustrates a flat cable 40B.

The monofilaments 41 may be unfused or fused together depending on thedesired characteristics. If the monofilaments 41 are fused together, thepolymer member 40 has mechanical characteristics similar to that of asolid rod. If the monofilaments 41 are not fused together, the polymermember 40 has mechanical characteristics similar to that of a cable. Acable, as opposed to a solid rod, is more flexible and is able towithstand more fatigue due to repeated bending. As such, a reinforcementlayer 32 utilizing braided polymer members 40 comprising a plurality ofunfused monofilaments 41 provide a shaft 12 that is more flexible andmore durable. These features are significant because the catheter 10must be able to navigate tortuous vasculature and withstand harshhandling conditions.

The monofilaments 41 may be made of a liquid crystal polymer (LCP)available under the trade name VECTRAN. Each monofilament may have acircular cross-section having a diameter of 0.0007 inches. Each polymermember 40 may comprise two (2) to ten (10), and preferably five (5)monofilaments 41 which, as stated previously, may be fused or unfused.If the monofilaments 41 are unfused, the monofilaments of the polymermember 40 are typically arranged side-by-side to essentially define aflat cable 40B as shown in FIG. 5B. It is possible, however, that themonofilaments be arranged in any manner to collectively define a flatcable 40B, a round cable 40A, or any other desired geometry.

Furthermore, if the monofilaments are arranged to collectively define aflat cable 40B, the flat cable 40B may be twisted along the length ofthe catheter shaft 12. Specifically, the flat cable 40B has a pair ofmajor sides 43 and a pair of minor sides 45. Each of the major sides 43faces the lumen 18 at various points along the length of the shaft 12.The flat cable may have random twists or a twist every 7.5 inches,depending on manufacturing conditions. Twisting the flat cable 40B mayprovide the advantage of improved guide wire movement due to ridgesformed on the inside surface of the inner layer 36.

The metallic member 42 may be formed of stainless steel or a highlyradiopaque material such as gold, tungsten, iridium, or an alloythereof. If a plurality of metallic members 42 are utilized, one or moreof the metallic members 42 may comprise stainless steel to providesuperior strength and one or more metallic members 42 may comprise ahighly radiopaque material to provide enhanced radiopacity. Althoughstainless steel provides higher radiopacity relative to most polymers, amore dense material such as those identified above are preferred forpurposes of radiographic visualization. The metallic members 42 may havea rectangular cross-section or a circular cross-section, depending onthe desired mechanical characteristics. Metallic member 42 may have acircular cross-section with a diameter of approximately 0.0016 inches tominimize profile. As seen in FIGS. 2 and 4, the longitudinal member 34comprises a longitudinally extending spine.

Longitudial member 34 is disposed between the reinforcement layer 32 andthe tie layer 38 to provide enhanced resistance to elongation as thecatheter 10 is removed from the patient's body. Longitudial member 34may be an LCP flat cable, similar to cable 40B.

When the polymer members 40 and the metallic member(s) 42 are braided,the reinforcement layer 32 provides superior flexibility and softness byvirtue of the polymer members 40 in addition to superior radiopacity andkink resistance by virtue of the metallic member(s) 42. These combinedfeatures are not found in prior art intravascular devices.

The proximal region 14 of shaft 12 includes an outer layer 30 formed byinterrupted layer coextrusion (ILC) as described in U.S. Pat. No.5,622,665 to Wang, which is hereby incorporated by reference. The ILCportion 44 of outer layer 30 includes a proximal portion 47 formed of arelatively high durometer polymer and a distal portion 49 formed of arelatively low durometer polymer. By virtue of the ILC process, theproximal region 14 gradually transitions from the relatively highdurometer polymer 47 to the relatively low durometer polymer 49. Thetransition between the relatively high durometer polymer 47 to therelatively low durometer polymer 49 is graphically illustrated bytransition line 46. However, transition line 46 is typically not visibledue to the intermixing of polymers during the ILC process. The ILCportion 44 may be formed of a suitable polymer such as polyether blockamide having a wall thickness of approximately 0.0025 inches. Forexample, the proximal ILC portion 47 may be formed of PEBAX™ 7233, whichhas a durometer of 72D and the distal ILC portion 49 may be formed ofPEBAX™ 3533 having a durometer of 35D.

The proximal region 14 of the outer layer 30 abuts the distal region 16of the outer layer 30 at junction line 48. The distal region 16 of theshaft 12 includes a proximal portion 50 and a distal portion 52. Boththe proximal portion 50 and the distal portion 52 of the distal region16 may be formed of the same or different polymers which have adurometer less than the durometer of the distal portion 49 of the ILCsection 44. The distal portion 52 of the distal region 16 may have thesame or lower durometer than the durometer of the proximal portion 50.The proximal portion 50 and the distal portion 52 may be formed of apolyether block amide polymer such as PEBAX™ 2533 having a durometer of25D. The proximal portion 50 encapsulates the radiopaque marker band 60.

Radiopaque marker band 60 may be formed of gold, tungsten, iridium, oran alloy thereof. The radiopaque marker band 60 is disposed over thereinforcement layer 32 and may optionally be swaged onto thereinforcement layer 32. The radiopaque marker band 60 may optionally beadhesively secured to the reinforcement layer 32 or held in place by theencapsulating proximal portion 50.

The distal portion 52 of the distal region 16 abuts the distal ends ofthe various layers 36, 38, and 32 and forms a lap joint with proximalportion 50 along junction line 54. Junction line 54 between the proximalportion 50 of the outer layer 30 and the distal portion 52 is notpresent if the proximal portion 50 and the distal portion 52 are made ofthe same material, i.e., the proximal portion 50 and the distal portion52 form a single unitary piece. Encapsulated marker band 60 may have alength of approximately 1.0 mm and may be positioned approximately 0.5to 1.5 mm proximal of the distal end of the shaft 12. Distal portion 52may extend approximately 0.5 to 1.0 mm beyond the distal end of theinner layer 36, tie layer 38 and reinforcement layer 32 to form anatraumatic soft tip.

FIG. 4 is an alternate embodiment of the elongate shaft 12 illustratedin FIG. 2. Specifically, FIG. 4 illustrates an alternative arrangementof the outer layer 30 of the distal region 16 of the elongate shaft 12.Except as described herein, all aspects of the embodiment illustrated inFIG. 4 are the same as those described with reference to the embodimentillustrated in FIG. 2.

Distal region 16 includes a proximal portion 70 and a distal portion 72.Proximal portion 70 and distal portion 72 may be formed of the samematerials as proximal portion 50 and distal portion 52, respectively, asdescribed with reference to FIG. 2. Distal portion 72 encapsulates theouter surface and distal face of the marker band 60. Distal portion 72and proximal portion 70 are connected by a lap joint as defined byjunction line 74. Junction line 74 between the proximal portion 70 andthe distal portion 72 is not present if the proximal portion 70 and thedistal portion 72 are formed of the same or similar materials. Distalportion 72 is approximately 2.5 to 3.0 mm in length and extendsapproximately 1.0 mm beyond the distal ends of the inner layer 36, thetie layer 38, and the reinforcement layer 32 to form an atraumatic tip.

The elongate shaft 12, including the embodiment illustrated in FIG. 2and the embodiment illustrated in FIG. 4, may be manufactured by anumber of suitable manufacturing processes including the processdescribed hereinafter. The inner layer 36 and the tie layer 38 may beobtained prefabricated from a suitable vendor, such as H.V.Technologies, and provided as discrete tubes or on a spool as acontinuous tube. Longitudial member 34 is then disposed on the tube ofinner layer 36 and tie layer 38. Optionally, the longitudial member 34may be applied during the braiding step. The reinforcement layer 32 isthen braided over the longitudial member 34 and the tube of inner layer36 and tie layer 38. The braided subassembly is subsequently cut to thedesired length. The marker band 60 is slid over the reinforcement layer32 into position adjacent the distal end 20 of the elongate shaft 12.The proximal portion 50,70 of the distal region 16 is slid over thereinforcement layer 32 adjacent the marker band 60. The proximal region14 comprising a prefabricated ILC tube 44 is slid over the proximal end22 of the elongate shaft 12. A heat shrink tube (e.g., FEP) is thenplaced over the shaft 12 components and the composite subassembly ispulled through a heated die. The die is heated to 380°-430° F. causingthe components of the shaft 12 to be fused and compressed together bythe combined heat and radial force. The heat shrink tube is thenremoved, exposing the completed shaft 12 subassembly. The manifold 24and the strain relief 28 are then attached to the proximal end 22 of theelongate shaft 12 using conventional techniques. The catheter 10 is thentested for minimum performance criteria including burst pressure. Thedistal end 20 of the elongate shaft 12 is then trimmed to the desiredlength, and the distal portion 52,72 of the distal region 16 isthermally fused thereto by, for example, inserting a mandrel into thelumen 18 and heating the tip 20 at 350° F. for twenty-six (26) seconds.A lubricious coating is then applied to exterior of the catheter shaft12.

Those skilled in the art will recognize that the present invention maybe manifested in a variety of forms other than the specific embodimentsdescribed and contemplated herein. Accordingly, departures in form anddetail may be made without departing from the scope and spirit of thepresent invention as described in the appended claims.

What is claimed is:
 1. An intravascular catheter comprising an elongateshaft having a proximal region, a distal region and a lumen extendingtherethrough, the shaft including a reinforcement layer comprising alongitudinal spine member and a braid, the braid having a metallicmember and a polymer member, wherein the polymer member comprises aplurality of monofilaments.
 2. An intravascular catheter as in claim 1,wherein the monofilaments are arranged to collectively define a roundcable.
 3. An intravascular catheter as in claim 1, wherein themonofilaments are arranged side-by-side to collectively define a flatcable.
 4. An intravascular catheter as in claim 1, wherein themonofilaments are arranged side-by-side to collectively define a flatcable having a first major side and a second major side, and wherein thefirst major side faces the lumen of the shaft for a first length and thesecond major side faces the lumen of the shaft for a second length. 5.An intravascular catheter as in claim 1, wherein the longitudinal spinemember comprises a polymer.
 6. An intravascular catheter as in claim 5,wherein the longitudinal spine member comprises a plurality ofmonofilaments.
 7. An intravascular catheter as in claim 6, wherein thelongitudinal spine member comprises LCP.
 8. An intravascular cathetercomprising an elongate shaft having a proximal region, a distal regionand a lumen extending therethrough, the proximal region including aninner polymer layer, a reinforcement layer and an outer polymer layer,the reinforcement layer comprising a longitudinal spine member and abraid, the braid having a metallic member and a polymer member, whereinthe polymer member comprises a plurality of monofilaments.
 9. Anintravascular catheter as in claim 8, wherein the monofilaments arearranged to collectively define a round cable.
 10. An intravascularcatheter as in claim 8, wherein the monofilaments are arrangedside-by-side to collectively define a flat cable.
 11. An intravascularcatheter as in claim 8, wherein the monofilaments are arrangedside-by-side to collectively define a flat cable having a first majorside and a second major side, and wherein the first major side faces thelumen of the shaft for a first length and the second major side facesthe lumen of the shaft for a second length.
 12. An intravascularcatheter as in claim 8, wherein the longitudinal spine member comprisesa polymer.
 13. An intravascular catheter as in claim 12, wherein thelongitudinal spine member comprises a plurality of monofilaments.
 14. Anintravascular catheter as in claim 13, wherein the longitudinal spinemember comprises LCP.
 15. An intravascular catheter comprising anelongate shaft having a proximal region, a distal region and a lumenextending therethrough, the proximal region including an innerlubricious polymer layer, a reinforcement layer and an outer layer, eachlayer having a distal end, the outer layer including a proximal portionand a distal portion, the proximal portion of the outer layer comprisinga first material having a first durometer, the distal portion of theouter layer comprising a second material having a second durometer lessthan the first durometer, the reinforcement layer comprising alongitudinal spine member and a braid, the braid having a metallicmember and a polymer member, wherein the polymer member comprises aplurality of monofilaments, the distal region of the shaft including anatraumatic tip layer surrounding at least a portion of the reinforcementlayer, the tip layer including a distal portion that extends distallybeyond the distal ends of the inner layer and the reinforcement layer,the tip layer comprising a third material having a third durometer lessthan the second durometer.
 16. An intravascular catheter as in claim 15,wherein the monofilaments are arranged to collectively define a roundcable.
 17. An intravascular catheter as in claim 15, wherein themonofilaments are arranged side-by-side to collectively define a flatcable.
 18. An intravascular catheter as in claim 15, wherein themonofilaments are arranged side-by-side to collectively define a flatcable having a first major side and a second major side, and wherein thefirst major side faces the lumen of the shaft for a first length and thesecond major side faces the lumen of the shaft for a second length. 19.An intravascular catheter as in claim 15, wherein the longitudinal spinemember comprises a polymer.
 20. An intravascular catheter as in claim19, wherein the longitudinal spine member comprises a plurality ofmonofilaments.
 21. An intravascular catheter as in claim 20, wherein thelongitudinal spine member comprises LCP.